The invention concerns radio frequency identification (RFID) systems, and more particularly concerns prefetching manifest data in anticipation of reading RFID tags.
As RFID tags become less expensive, they are increasingly being used to track items through production and distribution channels. For example, a shipment of items may be sent from a manufacturer to a warehouse, or from a warehouse to a retail outlet, where the items are tracked by RFID tags. When such a shipment arrives, it is validated. This entails reading each of the RFID tags, and comparing data read from the tags with data from a manifest that describes the expected contents of the shipment, in order to determine whether, for example, all of the expected items are accounted for, and that the items that arrive are indeed the items that were expected. In this way, a determination is made as to whether the items comply with the manifest.
In order to determine whether the items comply with the manifest, RFID tags associated with the items are read by an RFID tag reader. When a tag is read, the tag reader sends tag data up to an RFID edge controller, which may service a number of other tag readers as well. The edge controller then passes the data to a server, such as an RFID premises server, which has access to a database of manifests. The server compares the tag data with manifest data from the appropriate manifest, and reports the result of the comparison to the edge controller. If the item in question comports with the manifest, the edge controller so indicates, for example by audibly beeping or displaying a green light. This is repeated for each item of the shipment, thus to determine whether the shipment complies with the manifest.
Although this process works well on a small scale, large shipments of items require significant processing power and communication bandwidth. Moreover, since the edge controller and the server may service a number of different tag readers and process a number of different shipments of items simultaneously, resource constraints may emerge. For example, equipment buffers may fill and network delays may arise in the path between the edge controller and the server, thereby degrading responsiveness and limiting the effectiveness of this traditional approach as shipping traffic becomes more intense. Thus, there is a need for a more efficient way of determining whether items of a shipment tracked by RFID tags conform to an associated manifest.